p21 is a cell cycle-regulating protein that is encoded by CDKN1A gene and belongs to the CIP/KIP family. This protein has the function of inhibiting cell cycle progression at the G1 phase and the G2/M phase by inhibiting the effect of a cyclin-CDK complex through binding to the complex. Specifically, the p21 gene undergoes activation by p53, one of tumor suppressor genes. It has been reported that upon activation of p53 due to DNA damage or the like, p53 activates p21 so that the cell cycle is arrested at the G1 phase and the G2/M phase.
p21 is overexpressed in a variety of human cancers including prostate, cervical, breast and squamous cell carcinomas and, in many cases, p21 upregulation correlates positively with tumor grade, invasiveness and aggressiveness. See, e.g., Chang et al., Proc. Natl. Acad. Sci. USA, 2000, Vol. 97, No. 8, pp. 4291-96. Also, up-regulation of p21 has been reported to be associated with tumorigenicity and poor prognosis in many forms of cancers, including brain, prostate, ovarian, breast, and esophageal cell cancers. See, e.g., Winters et al., Breast Cancer Research, 2003, Vol. 5, No. 6, pp. R242-R249. Also, the disease can be age related diseases, including atherosclerosis, Alzheimer's disease, amyloidosis, and arthritis. See, e.g., Chang et al., Proc. Natl. Acad. Sci. USA, 2000, Vol. 97, No. 8, pp. 4291-96.
Therapeutics for inhibition of p21 expression will require highly potent siRNA sequences and structures.
What is needed are siRNA sequences, compounds and structures for inhibition of p21 expression.